Interval training, which means alternating between a fast pace that leaves your breathless, and a slower pace that allows you to recover, has long been known as a good way to train athletes who want to increase their speed and endurance. But it’s also a great way to burn excess fat, not just when you’re doing interval training, but even during more moderate workouts.
A study conducted at the Universityof Guelphin Ontarioshowed that not only can cardiovascular fitness improve dramatically, but the women also burned 36 percent more fat when exercising moderately for an hour after the interval training.
Many people do not like to push themselves hard enough while exercising to recruit new muscles fibers. But with the push and rest interval workout, high-intensity exercise can feel more tolerable. And once you train those extra muscle fibers, they work harder for you, burning fat any time you’re active.
Another factor that enhances fat burning is that hard exercise stimulates changes in mitochondria, the cells in our bodies that convert fuel into energy. They start burning fat preferentially over carbohydrates. Because of these two changes in energy usage, it’s thought that interval training may help to lower the risk of metabolic syndrome — a condition identified by obesity, insulin resistance, high cholesterol and high triglycerides, which is considered a risk for cardiovascular disease.
Pushing yourself to 80 percent or 85 percent of your target heart rate could provoke a heart attack or stroke in at-risk exercisers, so check with your doctor before you take on any kind of strenuous exercise if you have a history of heart disease, diabetes or stroke, or if you’ve got joint problems.
Once or twice a week can make all the difference, and you may find you like the focus and the feeling of kicking butt and then kicking back.
 Talanian JL et al. Two weeks of high-intensity aerobic interval training increases the capacity for fat oxidation during exercise in women. Journal of Applied Physiology. April 2007; 102:4, 1439-47.